Separable electrical connection



' W. c. TREGoNlNG SEPARABLE ELECTRICAL coNNEcToN Filed Ja'n.16, 192s 2sheets-sheet 1 i M M INVENTOR.

ATTORNEYS' W. C. TREGONING SEPARABLE ELECTRICAL; coNNEcTIoN Fled Jan.`16, 1923 2 Sheets-Sheet 2 INVENTOR.'

w27/idf?? C' 75190277@ ed, have in many instances involved Patented July17, 1928.

WILLIAM c. TBEGONING, or CLEVELAND. HEIGHTS, oIIIo.

` sErAnABLE ELECTRICAL CONNECTION.

Application led January 16, 1923. Serialv No. 613,063.

This invention relates to improvements in a separable electricalconnection, and method of making the same. While certain of thestructure illustrated as embodying the 1nvention is particularly adaptedfor a sepa-- rable attachment plug, it is to be under- 4stood that theinvention. is equally applicable to so-called convenience outlets in thewalls or base-boards of buildings, as W'ell as to connections withvarious pieces of electrical apparatus, wherein fixed connection bladesare secured to the base of, the structure and an element with bladerecesses on the live end of a flexible cable is engaged thereover. lTheinvention contemplates the production of an electrical connection havinga minimum number of fastening elements" and the contact members of whichare so anchored in the body that they will be maintained in operativeposition. under all conditions of severe usage.

Electrical connections, and more especially separable plugs, asheretofore constructa large number of parts which, while holding theseveral elements of the assembled plug in rigid position, involve anextensive operation in assembling. Likewise in the separable plugs andlike connections in common use, it is very difficult to seat the contactblades in the contact recesses because of the diiiiculty in bringing theends o f the blades intg register with the openings of said recesses.

It is the object of the invention to simplify the structure of theseparable plug to the point Where it may be manufactured with theminimum Waste, of material and the maximum of strength, as Well as topermit the several elements making up the device to be assembled incomplete forni with a small amount of labor. It is also an object of theinvention to provide a plug orsiinilar connection with guide meanswhereby the ends of the blades may be directed into position to registerWith the contact recesses and thus permit the coacting parts to beassembled largely through the sense of touch. Other objects-of theinvention will appear in the course of the following description. To theaccomplishment of the foregoing and related ends, said invention,

then, consists of the means hereinafter fully described and particularlypointed out in the claims.

The annexed drawing andthe following description set forth in detailcertain structure embodying the invention and method of making the same,such disclosed means and method constituting, however, but several ofvarious forms in which the principle of theinvention may be used.

In said annexed drawing Fig. 1 is a central longitudinal sectional viewof a separable attachment 'plug em- 65 bodying the invention; Fig. 2 isan end view of the cap section of the plug Fig. 3 is a view partially insection, showing one of the blades embedded in the cap section; Fig. 4is a perspective view of blades before insertion in the cap section;Fig.- 5 is a sectional view of the inner end of the base section; Fig. 6is an end view of the inner end of the base section; Fig. 7 1s aperspective View of the the cap section showing the guide grooves; Fig.8 is an end View of theinner end of' a modified form of the basesection; Figs. 9 and l0 are detailed views in perspective showing themodified contact elements used 80 With the device shown in Fig. 8; Fig.11 is a view showing a plate for a wall or base board having the guidegrooves and other 'eatures of the base section of the electricalconnection; and Fig. l2 isla central longi- 85 tudinal sectional View ofa separable attachment plug of the modified form shown in Figs. 8, 9 and10.

While various other embodiments of the invention are within the scope ofthe claims, 9o

forms thereof 'is one of the most complete incorporated in the separableplug type of connection.

The plug in its tov be separably associated. The base section has a body3, of non-conductive material, such as bakelite, having a'substantiallycylindrical form and having screw threads 4 one of the outer end ofpreferred form comprises a base section 1, and a cap section 2, adaptedintegrally formed about its circumference loo adjacent one end, adaptedto be engaged by a screwthreaded section 5 formed'upon the standardcontact shell 6, which is adapted to be firmly secured to the end ofsaid base section, and which constitutes the means of engaging said lugin the usual ,electric socket terminal not shown). The base section justreferred to is provided with a flattened outer face 7 having a pair ofhelical,

or inclined, segmental grooves 8 formed 110 therein at' a point midwaybetween theV center and the circumference of said face. Each of saidgrooves -is preferably of somewhat less than semi-circularextent and oneend of each of said grooves merges with the flat face of said plug, andis preferably beveled on its outer side and widened `at its outer end.Each groove is provided on its inner side with a straight wall 9, whilethe other end of said groove is within the body of the plug at a pointin alignment with the opening of one'of the blade contact recessesformed longitudinally of the plug and hereinafter described in detail.ln this manner, when the ends of the blades'upon the cap member of theplug are placed against the upper face of the base member of said plug,and rotated, they will ride upon the 1nclined or beveled portions of thegrooves and be centered when brought into contact with the straightinner sides thereof. Upon being further rotated said blade ends willstrike the end wall or abutment 10 provided in alignment with one sideof each of the respective blade contact recesses, and be thus broughtinto registry with said recesses. The blades may then be forced'downwardly into tight engagement with the contact members in saidrecesses. Centrally of the end of the plug, opposite the iat face justdescribed, a central projection 11 is provided, having iiattened sides12 meeting with angularly disposed seats or ledges 13 against whichcontact leaves are adapted to bear. These contact leaves 14, 15, areadapted to be positioned in recesses 16, 17, extending longitudinallythrough the base member of the plug, the ends of the recesses upon thefiat face of the tbase member intersecting one end of each of therespective helical grooves and the other ends of said recesses definingthe outer margins of the ledges or seats at either side of the centralprojection. Said ledges are formed at a slight distance below the endsurface 18 of the main portion of the base section, and notches 19, inalignment with said ledges, are formed outwardly of saidv blade contactrecesses.

The contact members for the blades in the preferred form of theseparable plug, are formed simply of ribbon'strips 21, 22, of bronze orother suitable metallic elements,

and. are bent at their lower ends to form blade contact springs 23, 24.They are provided adjacent their upper ends with shoulders 25, 26, toengage the ledges upon the end of one of said contact members is formedas 'an outwardly extending spring arm 27 member is bent so as to conformto the rectangular outline of thel central extension upon said plug andform the central contact member 28 thereof. The shoulder 25, providedupon said last-mentioned contact mem ber, is held in position upon theledge or seat 13 by means of the flange 31 of said shell 6 after a smallblock 32 of insulating material has been inserted above said shoulder.In this manner, the shell will be insulated from the stripof metalforming the central Contact member and will be brought into firm contactwith the end of the other strip of metal for which the shell itself isthe contact terminal when screwed into an electrical socket terminal ofstandard form.

In order to prevent the shell from shifting its position when screwedupon the base member, a pair of notches or depressions 33 are formed inthe body of said base member at either side of the central extension ofsaid base member at points intermediate of the socket apertures, and theflange of said shell is depressed into said notches by any suitablemeans.

In Figs. 8, 9, and 10, is illustrated a modified form of base member andcontact elements, the principal difference between said member and theform heretofore described comprising the provision of a pair of lateralears 41, 42, upon each of the metal contact members 43, 44, for theblades, and corresponding lateral notches or seats 45, 46, at the sidesof the recesses 47 for said blade contacts, against which seats saidears are adapted to engagel As is shown in Figs. 9 and 10 of thedrawing, the contact members 43 and 44 in the modified form of the basemember, differ in certain respects fromthose in the preferred form ofbase member. Thus, the contact member 43 which conveys the electricalcurrent from the shell is not bent upon itself to form the springcontact arm 48, but said arm is -bent directly outwardly toward theshell; and the contact member 44, instead of being bent to form ashoulder against which a block of insulating material is seated, has atongue 49 struck outwardly against which the insulating block bears whensaid block is pressed downwardly by the flange of the shell.

The cap section of the plug is adapted to be used with either form ofbase mem! ber heretofore described and is of the standard form with acentral aperture 50 for the iiexible conductor cable. bers 51 are formedfrom sheet metal by cutting out a series of angle bars nested, onewithin the other, and thus occasioning practically 11o wastage ofmaterial. The angle bars so produced are wiped into cylindrical Theblade memform at one end to provide a sleeve 52 which is thenscrew-threaded to receive the binding screws of the standard type.'Excepting for the formation of said screw socket-s, the

metal for the blades lies in a single plane. No sharp angles occur astlie sleeve or cylindrical'po'rtion involves merely the' rolling of themetal strip and not its being displaced laterally. However, in additionto the holding effect to be obtained by embedding the blades in theinsulating material forming the cap member of the plug, it has beenfound desirable to provide a tongue or lateral extension 53 adjacent theapex of said angle bars, so disposed as'to lie within the body of theblock at approximately an angle of 45 degrees to the plane of theblades. In this manner, an anchorage of great effectiveness is providedfor each of said blades.

The exterior finish of the detachable section of the plug is preferablythat shown in Fig. 1 wherein a knurled edge 54 is formed extending overa large area adjacent the` upper circumference of said section. `In thisway ample gripping surface is provided for' rotating the cap member ofthe plug with the blades pressed upon the top face of the lower sectionuntil they strike the guide grooves and are brought into register withthe blade sockets in the manner heretofore described.

The manufacturing of the top section of the plug is carried on in asuitable molding apparatus, pins being inserted in the screw sleevesuntil after the hardening of the in- ,sulating material about the baseof the blade sections.

It will also be noted that at the inner angle of each of the bladesections a fillet 55 is provided, such fillet not only serving as avstrengthening means for the blade, but also as a guide for the conductorcable ends, in conformity with the safety requirements .in force in manyplaces. Ihus the conductor cable end rides against. the inclined face of`the fillet as the binding screw is tightened, and seats properlybeneath the head of said screw. 'Without such fillet the cable end couldswing away from the lbinding post and short circuit through contact withthe other cable end or blade section.

At Vthe upperrend of each of the blades a depression or recess 61isprovidedon the outer side, said depression having straight side wallsand a bottom substantially V- shaped in longitudinal section. These de#pressions are adapted to -be engaged by pressed up dome-like projectionsor lugs 62 formed at appropriate positions along the inner sides of theblade contact members.

As is clearly shown in Fig. 1l, the base member may 'be in thev form ofa wall plate 63, the guide grooves functioning in the same manner aswhere the other type o base memberis employed. When the connectionblades mounted directly upon saidarticle and the guide slots and'contacts in the cap section in order that danger of shock may be avoidedthrough handling a cap section with live blades.

Other modes of applying thel principle of i my invention may be employedinstead of the one explained, change being made as relgards thestructure or methodherein disclosed, provided the means stated by any ofthefollowing claims or the equivalent of such stated means be employed.

I'therefo're particularly point out-and distinctly claim as myinvention 1. 1n an article of the character described, the combinationof a cap section having a air of contact blades and a base section, saidase section having a pair of longitudinal blade contact recesses, seatsformed adjacent said recesses, contact elements in said recesses havingangular portions adjacent thereto for engagement with said seats, and acontact shell provided With a straight inwardly extending flange at itsupper edge parallel to the angular portions of said contact elementsvfor pressing the same firmly against said seats.

2. A separable attachment lug base member having a pair of longitu inalblade contact recesses, a projection formed at the outer end of saidbase member between said recesses, a contact element positioned in oneof said recesses and extending over the end of rber having a pair oflongitudinal blade con' tact recesses, contact elements in saidrecesses, a projection formed at the outer end of said base memberbetween said recesses, a pair of seats formed in said base, memberadjacent said respective recesses, a contact vsaid central projection, ashoulder on said element positioned in one of said recesses andextending over the end of said central projection, a shoulder on saidcontact element for engagement with one of said seats, an insulatedblock seated over said shoulder, a second contact element positionedwithin the other blade recess, ashoulder formed on said contact memberfor engagement with the other of said seats, a free resilient end',provided on said second contact member, a screw-threaded section formedupon the body of said base member, and a flanged contact shell adaptedtobe engaged upon said v screw-threaded section of said base member tocoact ivith said shoulders to hold said Contact members in operativeposition.

4. A separable attachment plug base member having a pair of longitudinalcontact recesses, contact elements in said recesses, and downwardly andinwardly inclined faces 'adjacent said recesses on one side for guidingthe ends of the blades into alinement with said blade recesses. andupstanding vertical walls adjacent said recesses on the opposite sides,to prevent movement of -said blades pasty said recesses.

Signed by me, this 11th day of January, 1923. i

VILLIAM C. TREGONING.

